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305 TBI power potential with free mods?


turbogrill
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Hi,

 

Hard to ignore the SBC engine for a possible future swap, it's heavy and old school but so cheap and kits are available.

The SBC 305 TBI engine found in everything (trucks, camaros, etc) has an astonishing power output of 170 hp at the crank. SBC community says throw the engine away or get better head, cam and intake.

However that is too many points and 180hp is about the limit before swap points starts to increase too much.

 

I would think that it would be possible to extract a little more than 34 hp/l out of these engines with 0pts modifiers. Anyone has any experience doing this?

 

These seems to be common 0pts mods:

- Exhaust, the 170hp was with restrictive exhaust

- TBI porting (dremel in garage)

- Megasquirt

- Air intake 

 

Would >200hp crank be possible with the above mods?

 

The power curve is very interesting on these engines, it's flat and starts early. 

 

 

 

 

  

 

Edited by turbogrill
typo
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34 minutes ago, turbogrill said:

Hi,

 

Hard to ignore the SBC engine for a possible future swap, it's heavy and old school but so cheap and kits are available.

The SBC 305 TBI engine found in everything (trucks, camaros, etc) has an astonishing power output of 170 hp at the crank. SBC community says throw the engine away or get better head, cam and intake.

However that is too many points and 180hp is about the limit before swap points starts to increase to much.

 

I would think that it would be possible to extract a little more than 34 hp/l out of these engines with 0pts modifiers. Anyone has any experience doing this?

 

These seems to be common 0pts mods:

- Exhaust, the 170hp was with restrictive exhaust

- TBI porting (dremel in garage)

- Megasquirt

- Air intake 

 

Would >200hp crank be possible with the above mods?

 

The power curve is very interesting on these engines, it's flat and starts early. 

 

 

 

 

  

 

Yes, BTW the TBI is the restriction above 4500-5000rpm.

If this is a used engine: check/replace the rod bearings and oil pump (high volume not high pressure)

Time to speak to both @TiredBirds and @mender

Edited by Team Infiniti
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52 minutes ago, Team Infiniti said:

Yes, BTW the TBI is the restriction above 4500-5000rpm.

If this is a used engine: check/replace the rod bearings and oil pump (high volume not high pressure)

Time to speak to both @TiredBirds and @mender

you can make 300 pretty easy with a 305. Use a carb'd intake. The TPI dies out at about 5k. Our 305 (88 roller motor) pulls hard to 6000. If you want details just ask.  This is our 84 (RIP) the same engine trans will be in the new 88 as well as all the suspension. 

 

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37 minutes ago, cj25 said:

In my opinion based on 35 years of  circle track racing sbc's of  different forms or another they are complete dogs with the stock cam, it will make the most usable hp mod available.

yes but it is fun to pass 350's with a 305.... And who wouldn't change the cam? FWIW the 305 5 speeds were faster in the 1/4 mile than the 350's because they were all automatics. Since this league goes by HP. and not actual cost a 305 isn't terrible. 

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200+ HP is possible for sure, the stock 305 TBI cam is absolutely tiny, maybe a generic stock replacement cam has a little more nowadays? I made about 200 WHP (+50-60HP) with a stock head TBI engine (not sure of the mods at the time), just basic stuff and a stock TPI cam about 15-20 yrs ago. It went mid-14s at 96 mph in a full weight street car Firebird on Walmart type tires. About 2 secs and 9 mph faster than stock. I think it picked up something like .5 sec and 4 mph just from headers/exhaust.

 

Might be some ancient info on the turdgen.org TBI section forums under “Beast5spdgta”.

 

I just so happen to still have the TBI Craig moates custom chip adapter stuff for custom DIY tunes and the whole car/engine in my yard!  It’s been pretty chewed up by rats, dogs and who knows what else.

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22 hours ago, turbogrill said:

Hi,

 

Hard to ignore the SBC engine for a possible future swap, it's heavy and old school but so cheap and kits are available.

The SBC 305 TBI engine found in everything (trucks, camaros, etc) has an astonishing power output of 170 hp at the crank. SBC community says throw the engine away or get better head, cam and intake.

However that is too many points and 180hp is about the limit before swap points starts to increase too much.

 

I would think that it would be possible to extract a little more than 34 hp/l out of these engines with 0pts modifiers. Anyone has any experience doing this?

 

These seems to be common 0pts mods:

- Exhaust, the 170hp was with restrictive exhaust

- TBI porting (dremel in garage)

- Megasquirt

- Air intake 

 

Would >200hp crank be possible with the above mods?

 

The power curve is very interesting on these engines, it's flat and starts early. 

If you want to swap in a SBC that will have some potential but still be under your 180 hp limit, look at mid to late '70s 350s. They had reasonable heads and a 4bbl intake. Good power potential is there with just a cam swap and some porting. 

 

https://www.powerperformancenews.com/tech/bolt-ons-for-beginners-sbc-power-mods/

Edited by mender
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